Power mains question: wire gauge

Dec 28, 2012 175 Replies

Too bad you aren't king huh?

The fact still remains the NEC says you build the system and then you pull the wire in. If you ever want to replace the wire with another configuration you will understand why. I also wonder how you keep the PVC cement off the wire if you use RNC.

That's the best idea I've heard yet.

Sadly, he had already located the compressor, installed the air lines, hooked it up before calling me to wire it. He placed it right next to the main air-user, the mechanic's bays. (It's an auto repair shop.)

Dave (OP)

I do understand. I know all about serviceability issues.

This is a single, STRAIGHT run with zero mid-span junction breaks. It would be fine. Ahhh... forget it.

Dang. Just buy 12/2 UG Nomex, bury it at 18" and forget the pipe.

It depends on several variables, including motor size, motor winding class, number of phases, design of motor start system, and some other things. Very small motors may start at 2x FLA, some very large (full voltage start) motors may require 20 to 30 x FLA.

?-)

AEE fans (Should I tell him that is 24?")

My old Cable TV days. Their burial depth requisite is 18". (at least in Ohio)

Hey, the less the content, the longer the thread. This is post #120, and it was decided long ago that the OP can use 12 or 14 gage wire.

They don't make them that that go fast enough to deal with the sewage you produce

You were talking about UF, not TV cable

Right. but in reference to my mistake, I was explaining why.

No problem. The advantage of using PVC conduit is that you can bury it

18" instead of the 24 you need for UF. The other is the ability to change your mind without needing a shovel Personally I would run 3/4" instead of the more common 1/2" because it is easier to pull the wires in, you can put bigger wire in the pipe and the cost differential is minimal. The labor is the same.

You lefties are always projecting your inadequacies.

Well I'm not interested in being quarrelsome but would you mind explaining why you would use copper piping for air lines. Copper has gotten more pricy rather than recently pricey so it would seem to be rather a waste to use it for air. Help me out here. What am I missing?

ote:

In North American Practice the electrical codes forbid assembling conduit around wire. The conduit must be built as a complete assembly and then you pull the wire from pull point to pull point.

I ran air around my shop and when I priced it out, 1/2" galvanized was cheaper than copper and a whole lot tougher. I was able to buy threaded pipe nipples in the sizes to do the whole thing without any threading dies.

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